- Harvey Atkin
- King Richard
- Kristen Bishop
- Kuppi
- Gina Clayton
- Additional Voices
- Jill Frappier
- Keroppi / Kerada (voice)
- Jennifer Griffin
- Keroppi's Mom
- Elva Mai Hoover
- Newton / Den Den / Issac (voice)
- Tracey Hoyt
- Keroleen / Meroleen (voice)
- Kazue Ikura
- Den Den
- Hadley Kay
- Additional Voices
- Kathleen Laskey
- Kerada's Mom
- Julie Lemieux
- Soak / Speedy (voice)
- Jeff Lumby
- Junk / Nelson (voice)
- Masae Maeda
- Koroppi
- Gordon Masten
- Guy
- Yoshiko Matsuo
- Keroppi
- Masako Miura
- Keroleen
- Sanae Miyuki
- Teru Teru
- Hiroko Nishi
- Pikki
- Nadine Rabinovitch
- Ruby
- Rino Romano
- Curtis / Kevin / The Gama's (voice)
- Ron Rubin
- Kevin
- Chika Sakamoto
- Tink
- Tabitha St. Germain
- Curtis / Wink / Aaron / Twinkle (voice) (as Paulina Gillis)
- John Stocker
- Movie Man / Wizard (voice)
- Tomiko Suzuki
- Ganta
- Chris Wiggins
- Narrator / Keroppi's Dad / Avalon (voice)
- Thick Wilson
- Santa Claus / Reindeer's (voice) (as Addison Bell)
- Kyôko Yamada
- Kyorosuke
- Michiyo Yanagisawa
- Noberun
- Frank Welker
- Baby Dolphins
